INA219/INA226 on ESP32 for Home Assistant (2026)

Quick Summary
This guide shows how to connect an INA219 or INA226 current/voltage sensor to an ESP32 over I²C, configure it in ESPHome, and monitor battery/solar voltage, current, power and energy in Home Assistant (optional MQTT). Includes wiring, address scanning, calibration tips, and common fixes for noisy or incorrect readings.

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1) INA219 vs INA226 (which one should you use?)

Both sensors measure bus voltage and shunt voltage to calculate current and power.

INA219

• Very common, very cheap breakout boards everywhere
• Great for “good enough” monitoring
• Often found with a 0.1Ω shunt on the board

INA226

• Typically better resolution/accuracy (depends on board + shunt)
• Better choice if you care about small currents and accuracy
• More common in “serious” power monitoring projects

Rule of thumb

• If you already have INA219 boards → use them, they work fine.
• If you’re buying new and want better accuracy → get INA226 + a good shunt.

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2) What you need

• ESP32 dev board (DevKitC, etc.)
• INA219 or INA226 breakout board
• Jumper wires
• Optional: a known load (e.g., 5W/10W resistor, DC lamp, USB load tester) for calibration

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3) Wiring (ESP32 ↔ INA219/INA226 over I²C)

3.1 I²C wiring (recommended defaults)

Use the ESP32 default I²C pins:

INA219/INA226	ESP32
VCC	3V3
GND	GND
SDA	GPIO21
SCL	GPIO22

Power the breakout from 3.3V so the I²C logic levels match the ESP32.

3.2 “Where does the sensor go” in the power line?

Both sensors measure current through a shunt. Typical breakout boards place the shunt on board between two screw terminals.

You’ll see terminals labelled something like:

• VIN+ / VIN- (or V+ / V-)

You wire it in series with the positive line:

• Battery/Solar positive → VIN+
• VIN- → your load/system positive
• Battery/Solar negative stays common ground (but see the note below)

3.3 Very important: common ground

For stable readings:

• The ESP32 ground and the system ground should be common (shared), unless you’re using isolation elsewhere.

If you’re doing solar/battery monitoring of a floating system and you’re unsure, start with a simple shared ground test setup first.

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4) Find the I²C address (scan it first)

Many boards use:

• INA219: often 0x40
• INA226: often 0x40 as well (but varies)

Use this ESPHome i2c scan config and check logs:

i2c:
  sda: 21
  scl: 22
  scan: true

Then in ESPHome logs you’ll see detected devices and their addresses.

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5) ESPHome configuration (Home Assistant native)

5.1 Base ESPHome template

esphome:
  name: esp32-ina-monitor
  friendly_name: ESP32 INA Monitoresp32:
  board: esp32dev
  framework:
    type: arduinologger:
api:
ota:wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  ap:
    ssid: "INA Monitor Fallback"
    password: !secret ap_passwordcaptive_portal:i2c:
  sda: 21
  scl: 22
  scan: true

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6) INA219 in ESPHome (recommended config)

sensor:
  - platform: ina219
    address: 0x40
    shunt_resistance: 0.1 ohm
    current:
      name: "Battery Current"
    power:
      name: "Battery Power"
    bus_voltage:
      name: "Bus Voltage"
    shunt_voltage:
      name: "Shunt Voltage"
    max_voltage: 32.0V
    max_current: 3.2A
    update_interval: 2s

Notes

• shunt_resistance must match your board’s actual shunt.
  • Many INA219 breakouts are 0.1Ω, but not all. Some use 0.01Ω.
  • If your current readings are “10× off”, this is usually why.
• max_voltage and max_current help calibration range choices.
• 2 seconds is a nice interval for dashboards; use 5–10s for low-noise logging.

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7) INA226 in ESPHome (recommended config)

sensor:
  - platform: ina226
    address: 0x40
    shunt_resistance: 0.01 ohm
    current:
      name: "Battery Current"
    power:
      name: "Battery Power"
    bus_voltage:
      name: "Bus Voltage"
    shunt_voltage:
      name: "Shunt Voltage"
    update_interval: 2s

Notes

• INA226 boards often come with lower-value shunts like 0.01Ω.
• Again: wrong shunt value = wrong current.

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8) Energy tracking (Wh / kWh) in Home Assistant

INA sensors provide power (W). To track energy (Wh/kWh) you integrate power over time.

In ESPHome, add a total_daily_energy sensor:

sensor:
  - platform: ina219
    address: 0x40
    shunt_resistance: 0.1 ohm
    power:
      name: "Battery Power"
      id: batt_power
    current:
      name: "Battery Current"
    bus_voltage:
      name: "Bus Voltage"
    update_interval: 2s  - platform: total_daily_energy
    name: "Daily Energy"
    power_id: batt_power
    unit_of_measurement: "Wh"

Then add it to the Energy Dashboard (usually you’ll want kWh; you can convert in HA using a template helper if needed).

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9) Calibration and accuracy tips (the stuff that makes it “trustworthy”)

9.1 Verify your shunt value

Look at the shunt resistor marking:

• “R100” → 0.1Ω
• “R010” → 0.01Ω
• “R005” → 0.005Ω

If you can’t read it or don’t trust the listing:

• Measure it with a meter that can measure low resistance (or do a voltage drop test with known current).

9.2 Use a known load

For a sanity check:

• Connect a known resistive load (e.g., 10Ω at 12V ≈ 1.2A)
• Compare INA reading vs multimeter

Adjust shunt value and/or scaling if needed.

9.3 Smooth noisy readings

If you see jitter:

• Increase update_interval to 5s
• Add a sliding window average filter in ESPHome:

filters:
  - sliding_window_moving_average:
      window_size: 6
      send_every: 3

Use it on current/power sensors.

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10) Common problems & fixes

Problem: current reading is ~10x too high/low

Cause: wrong shunt_resistance value.
Fix: set the correct shunt resistance for your board.

Problem: voltage looks right, current is 0A

Cause:

• sensor not placed in series correctly (VIN+ and VIN- swapped / load wired wrong)
• no load current flowing

Fix: re-check wiring direction and series placement.

Problem: I²C device not found

Cause:

• wrong SDA/SCL pins
• no common ground
• wrong address
• powered at 5V with no level shifting

Fix:

• enable scan: true and check logs
• power the module at 3.3V
• check solder joints on cheap boards

Problem: unstable readings when Wi-Fi transmits

Cause: power noise / ground bounce.
Fix:

• add decoupling near ESP32 and sensor (0.1µF + 10µF)
• reduce update rate
• keep wiring short

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11) Solar/Battery monitoring patterns that work well

Pattern A: monitor the load side of a battery system

• Battery → INA → load
• Use sensors:
  • Bus Voltage = battery/system voltage
  • Current = load current
  • Power = load power
  • Daily energy = Wh used per day

Pattern B: monitor charge current from solar controller

Put INA in series with the line you want to measure:

• Controller output → INA → battery
  This gives you “charge current” rather than “load current”.

Don’t try to measure “everything” with one INA unless your wiring makes that physically true.

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12) MQTT option (optional)

If you prefer MQTT:

mqtt:
  broker: 192.168.1.10
  username: !secret mqtt_user
  password: !secret mqtt_pass

Most ESPHome + Home Assistant users stick with the native API, but MQTT is fine for broker-centric setups.